Gemini Spies Strong Stellar Gusts in Nearby Massive Star

A dramatic infrared image released today by the Gemini Observatory
sheds new light on the early stages of the formation of giant stars in
our galaxy. The image, taken by the Gemini North telescope on
Hawaii's Mauna Kea, reveals remarkable details in a nebula of gas and
dust expelled from a young star named AFGL 2591. This expulsion is a
common feature in the formation of stars similar in size to the Sun,
but it is far less common in their massive counterparts.

"Almost everything in this set of infrared images would be invisible
with an optical telescope, since it is occurring within a dense
molecular cloud of gas and dust," says Gemini scientist Colin Aspin,
who made the observation. "Gemini's unparalleled sensitivity and
resolution in the infrared allows us to move beyond simply detecting
such structures in general to being able to study them in great
detail."

AFGL 2591 is located within the Milky Way more than 3,000 light-years
from Earth, in the constellation of Cygnus. Over the course of the
last few thousand years, it has created a vast expanding nebula larger
than 500 times the diameter of our solar system. The star is at least
10 times the size of the Sun, and over 20,000 times as bright, but
perhaps only one million years old.

The wispy white and blue structure in the expanding nebula to the
right of the young star is a huge outflow of gas and dust driven by
the infall of material onto the star's surface. Gemini scientists
believe that the outflow is likely occurring symmetrically around the
star - a second giant-sized expanding nebula to the left of the star
is hidden from view by a dense and extensive disk (or torus) of
material encircling AFGL 2591.

"We strongly suspect the outflow occurs on both sides of the star in a
bipolar structure, because we detect faint traces of gas at that
location which indicate interactions between the outflowing gas and
the material forming the parent molecular cloud," says Aspin, a
scientific staff member at the Gemini Observatory International
Headquarters in Hilo, HI.

"A unique feature of this object is a series of four distinct rings of
nebulosity. These rings suggest that the expulsion of the material is
not constant with time, but rather has occurred several times over the
lifetime of the object," he adds. "Studying the structure and
velocity of these rings, and their relation to the infalling material,
will allow us to better understand why such features are created and
what functions they serve."

This striking image is part of a series of early images taken with the
Gemini Near Infrared Imager (NIRI) instrument during its commissioning
on the Gemini North telescope. Once fully operational later this
year, NIRI will be the prime near-infrared instrument on Gemini
North.

The color image and others that show hints of the left-hand outflow
and more details in the right-hand structure are available on the
Internet in various file sizes (different files will go here).

The Gemini Observatory is an international collaboration that has
built two identical 8-meter telescopes. The telescopes are located at
Mauna Kea, Hawaii, (Gemini North) and Cerro Pachón in central
Chile (Gemini South), and hence provide full coverage of both
hemispheres of the sky. Both telescopes incorporate new technologies
that allow large, relatively thin mirrors under active control to
collect and focus both optical and infrared radiation from space.
Gemini North recently began science operations and Gemini South is
scheduled to begin scientific operations in August 2001.

The Gemini Observatory provides the astronomical communities in each
partner country with state-of-the-art astronomical facilities that
allocates observing time in proportion to each country's
contribution. In addition to financial support, each country also
contributes significant scientific and technical resources. The
national research agencies that form the Gemini partnership include:
the US National Science Foundation (NSF), the UK Particle Physics and
Astronomy Research Council (PPARC), the Canadian National Research
Council (NRC), the Chilean Comisión Nacional de Investigación
Cientifica y Tecnológica (CONICYT), the Australian Research
Council (ARC), the Argentinean Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET) and the Brazilian Conselho
Nacional de Desenvolvimento Científico e Tecnológico (CNPq). The
Observatory is managed by the Association of Universities for Research
in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF.
The NSF also serves as the executive agency for the international
partnership.